Killing it! Hamilton laps up Suzuka's 'insane' speed

World champion Lewis Hamilton wore the expression of a child in a candy store after utterly dominating Friday's free practice for the Japanese Grand Prix.

Leading Ferrari's Sebastian Vettel by 50 points with five races left this season, Hamilton underlined his purple patch of form by pushing his Mercedes more than 0.8 seconds quicker than the German in the afternoon session with a breath-taking lap.

"Suzuka has to be one of my favourite circuits, if not the favourite," said the Briton, who has won five of the last six races to close in on a fifth Formula One title.

"Every time we come to Suzuka, the cars just get faster and faster. It's incredible -- they don't make tracks like this anymore." Hamilton took his 70th chequered flag in controversial circumstances at Sochi last weekend when Mercedes ordered team mate Valtteri Bottas to let him pass.

But there was no charity on display on Friday as Hamilton dominated both sessions, his afternoon lap of one minute, 28.217 seconds knocking the stuffing out of Ferrari.

"This track is awesome," he whooped over the team radio. "I'm having the best day!" Hamilton pounded out fastest lap after fastest lap to leave Ferrari and Red Bull deflated, finding extra tenths where other drivers struggled at the iconic Japanese circuit, where top speeds reach 328kph (203mph).

"There's very little room for run-off," said Hamilton, who has won three times at Suzuka and four overall in Japan.

"A little touch of the grass and you're off in the wall. It's very cool, especially the first and second sectors are insane," he added.

"The first section is the best rollercoaster ride that I've felt in a Formula One car. I was like 'there are two or three corners where I know that I need to kill it this year' -- and I got straight up to it." But Hamilton is taking nothing for granted while it is still mathematically possible for Vettel to catch him in the title race.

"I just have to stay on it, keep working," said the 33-year-old.

"I'm just loving driving more than ever. When you get in the car it's just the best -- it's so fast. I'm just so grateful to have the opportunity to do what I do."